Jamieson, Fausset and Brown on Daniel 6:3

3. Daniel was preferred--probably because of his having so wonderfully foretold the fall of Babylon. Hence the very expression used by the queen mother on that occasion (Da 5:12) is here used, "because an excellent spirit was in him."

king thought to set him over the whole realm--Agreeing with Darius' character, weak and averse to business, which he preferred to delegate to favorites. God overruled this to the good both of Daniel, and, through him, of His people.